Enantioseparation and quality control of biperiden in pharmaceutical formulations by capillary electrophoresis

An original capillary electrophoretic method has been developed and applied for the enantioselective analysis of the antiparkinson drug biperiden in pharmaceutical formulations, using a modified cyclodextrin as the chiral selector. Baseline enantioseparation of the racemic compound was achieved in less than 7 minutes using an uncoated fused silica capillary (50 μm I.D. and 48.5, 40.0 cm, total and effective length, respectively), filled with a background electrolyte consisting of a 50 mM phosphate buffer at pH 3.5 supplemented with 3% (w/v) beta-cyclodextrin sulphate and applying a voltage of 20 kV, reversed polarity. Samples were injected by pressure (50 mbar, 90 s) at the cathodic end of the capillary and detection wavelength was 195 nm (bandwidth: 10 nm). A simple and fast pre-treatment procedure allowed the complete extraction of the drug from commercial formulations (sustained release tablets and ampoules for injections) without any interference from the matrix. Good linearity was found in the 1-50 µg/mL concentration range; the limit of quantitation was 1 µg/mL and the limit of detection was 0.4 µg/mL. Precision and accuracy were good, with RSD values always lower than 2.8% and a mean recovery value of 101.1%. The method was suitable for the quality control of biperiden in commercial formulations.